const switcher = document.querySelector('.btn');
switcher.addEventListener('click', function() {
     
    var className = document.body.className;
    if(className == "light-theme") {
    	document.body.className='dark-theme';
        this.textContent = "Dark";    
    }
    else {
    	document.body.className='light-theme';
        this.textContent = "Light";    
    } 

    console.log('current class name: ' + className);

});
